Hi,I bought a 999 on sale and testet recording. On the first run the sidescan image showed a very disturbing issue that can be described as a "bar code" phenomenon that gave all details a zigzag shape. I have then tested with recording with and without recording the 83 kHz channel, and found the issue disappeard when omitting 83 kHz. I can live with this in most situations, except when scanning downward at 50 kHz for getting subbottom profiles. I find this issue a bit disappointing, because its similar to issues reported already with the very first side imaging models many years ago. I have tried searching the forum on this subject, but found almost nothing. Does anyone know if there is any solution to this like some update or perhaps a very specific type of SD card should be used?

Added a Reefmaster snapshot that shows the difference between recording only 200 kHz and 200 plus 83 kHz. The lines in the middle are caused by reflections from the hull and should be smooth. Depth is about 20' (8m). The double arrow points at where 83 kHz was included.

Thanks Rickie, The original version is 7.640. The latest upgrade is 7.650, but according to specs it only deals with a few marginal mapping issues. Downgrading below the version that came with the unit is not recommended, as you know. We have to wait and see if Hummminbird presents fixes in future versions.